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Full text of "Practical Organic Chemistry"

104

PRACTICAL ORGANIC CHEMISTRY

solution of the calcium salt, add a solution of phenylhydrazine
acetate and a little sodium acetate. The -phenylhydrazoiie
separates on standing in minute yellow crystals, which can
recrystallised from alcohol. The neutral salts also
with sodium bisulphite and hydroxylamine.
G-lycollic Acid. If it is required to convert the oxalic acid
completely into glycollic acid, the same method is employee! as
described above, but the temperature is raised to 35° and the
number of ampere-hours is doubled. The separation is effected
as the calcium salt and precipitated with alcohol as already
described.
COOH.COOH + 2H2 = CH2OH + COOH + H2O
Properties.—Crystals m. p. 79—80° ; very soluble in water.
The air-dried calcium salt contains three molecules of water of
crystallisation and is soluble in So parts of water 15°, and in 19
parts at 100°. See Appendix^ p. 258.
PREPARATION 28.
Palmitic Acid, C15H31CO.OH.
Fremy, Annalen, 1840, 36, 44.
30 grins, palm oil.
24     „    caustic potash.
The caustic potash is dissolved in its own weight of water,
The palm oil is melted in a large basin on the water-bat! i,
and the potash solution added with constant stirring. THt;
mixture is heated for half an hour. Half a litre of boiling
water is poured in, and, after stirring well, 75 c.c. concentrated
hydrochloric acid are gradually added, and the heating" con-
tinued until the palmitic acid separates out as a transparent
brown oil on the surface of the liquid. It is allowed to cool, arid
the cake of impure acid removed and pressed between filter-
paper. The acid is now melted in a small basin on the water-
bath and decanted, from any water which may have separated,
into a retort (250 c.c.). It must be distilled in vacuo. TTie
neck of the retort is fixed into a small filtering tube, which servc-n
as receiver, as shown in Fig. 67. A few small pieces of ung^lazcd